The present disclosure is generally directed to absorbent and shrinkable materials. In particular, the present disclosure is directed to materials that shrink in one dimension and expand in another dimension when absorbing a liquid such as water or a bodily fluid.
Responsive materials that can potentially address many unmet consumer needs associated with existing products are needed. New applications of those responsive materials can also stimulate exploration and development of emerging products beyond current categories.
Related materials can include water shrinkable fibers; however, they are not hydrogels, they do not shrink to the same magnitude, and they do not possess elastic properties. Previous attempts at producing responsive materials include materials such as those described in U.S. Pat. No. 4,942,089 to Genba et al. related to shrinking fiber, water-absorbing shrinkable yarn, and other similar materials. Shrinking fibers that are hardly soluble in water and that are capable of shrinking in water at 20° C. by not less than 30% in not longer than 10 seconds are obtained, for example, by spinning, drawing, and heat-treating a carboxy-modified polyvinyl alcohol under specific conditions. Yarns made from a fiber of this kind in conjunction with nonwoven fabrics made by incorporating yarns containing such shrinking fibers in nonwoven fabrics that are shrinkable upon absorption of water have been proposed for tightly fitting edge portions of disposable diapers to the thigh.
Although capable of absorbing fluids, conventional hydrogels are generally soft and fragile in a hydrated state and brittle and hard in a dried or dehydrated state. Conventional hydrogels have poor mechanical properties with poor stretchability and notch-resistance.
In addition, U.S. Patent Application Publication Number 2015/038613 to Sun et al. describes a hydrogel composition, but does not disclose drying/dehydrating such a composition under stress. PCT Patent Application Publication Number WO06132661 to Muratoglu et al. describes a hydrogel that is made “tougher” by dehydrating the hydrogel after “deforming” the hydrogel using compressive force.
As a result, there is a need to enable production of a nonwoven with the attributes described herein.